The present invention relates to systems for processing waste water; more particularly, to such systems for handling biologically digestible materials in waste water generated typically in foods and potables manufacturing and serving, e.g., bakeries, breweries, dairies, restaurants, wineries, and the like; and most particularly, to a simple, small volume system for settling solids and adjusting pH in food process waste water to meet waste water quality standards for discharge into a municipal sewage system, including a method for static mixing in an industrial waste water settling tank to increase the percentage of recovery of entrained solids from the waste water.
As used herein, the term “food materials” should be taken to mean any and all biologically digestible organic materials, without limit; the term “food process waste water” should be taken to mean excess water and by-products, components beyond just water itself, used in the manufacture and/or use of food materials, which water must be treated to remove a portion of the dissolved and/or suspended food materials before being either sent to a waste water treatment facility, otherwise discharged to the environment, or hauled away for offsite handling.
Foods and potables manufacturing and handling typically require large volumes of input process water and generate substantial levels of biologically digestible materials dissolved and suspended in their resultant waste process water. Additionally, the pH of such waste water may be substantially acidic or alkaline. When directed without pre-treatment to municipal wastewater treatment facilities, such waste water can place a heavy and costly load on municipal waste treatment facilities. As a result, many communities impose a substantial cost on companies that generate such waste waters in the course of their operations. It is known to monitor the level of food materials in waste water output of companies and to levy a sewer surcharge on the companies accordingly. Many of these companies, for example, “microbreweries”, are relatively small in capitalization and output and thus are in need of a relatively inexpensive method and associated apparatus for pre-treating of process waste water to remove a substantial percentage of suspended food materials therefrom before the process waste water is discharged to a municipal sewer system. Fortuitously, the total volume of process waste water generated by many such operations is relatively small, on the order of 1000 gallons/day or less, and therefore is amenable to treatment by a method and apparatus in accordance with the present invention. Larger scale operations can also be supported by scaling up with multiple modules of the present invention.
Note: “Biological Oxygen Demand” (BOD), also known as Biochemical Oxygen Demand and as used herein, is the amount of oxygen needed by aerobic microorganisms to decompose all the organic matter in a sample of water; it is used in the eco-sciences as a measure of organic pollution. As used herein, the term “BOD” also means more generally the unit volume load, both dissolved and suspended, of such organic material in waste water.
Further, Total Suspended Solids (TSS) is a water quality measurement which, as used herein, is expressed as the unit volume load of suspended solids, both organic and inorganic, in water. It is listed as a conventional pollutant in the U.S. Clean Water Act.